Water Protection Activities in Washtenaw County

Challenge # 1: Arsenic
Arsenic is a naturally occurring element found in Washtenaw
County and throughout the earth’s crust. For residents, it may
pose a threat in groundwater. High concentrations of inorganic
arsenic in groundwater can
cause health problems when
the water is consumed,
especially over long periods
of time. A significant number
of wells in Washtenaw
County have arsenic levels
exceeding the Michigan Safe
Drinking Water Act standard
of 10 parts per billion (ppb)
What protection
activities address the
challenge of arsenic?
Time of Sale
Well Regulation
Michigan Safe Drinking
Water Act (Act 399)
(See Map 5). As a result individuals have drilled new wells or
installed treatment devises to lower the arsenic concentration to
a safe level.
Based on studies in other countries, long term exposure to high
arsenic levels (generally greater than 30 ppb) in drinking water
cause serious health problems including skin disorders, various
cancers, numbness in limbs, stomach pain, nausea and diarrhea.
The Safe Drinking Water Act was amended in 2001 to require
all public water systems to comply with a maximum
contaminant level (MCL) of 10 ppb for arsenic by January 23,
2006. The State of Michigan adopted the new 10 ppb standard,
which Washtenaw County adheres to by local code. The
previous standard for arsenic was 50 ppb.
Arsenic Response Objective:
Minimize the exposure and consumption of water with elevated
levels of arsenic in Washtenaw County.
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Arsenic Response Results:
Arsenic has been found in well samples in every township in
Washtenaw County; however, samples exceeding 50 ppb have
only been recorded in 5 townships; Saline, Dexter, Webster,
Sylvan, and Pittsfield. Of the 2,502 well sample records to
date, only 252 or 10.2% exceed the current level of 10 ppb.
Over 5,000 wells have been tested through the time of sale
program since 2000. Through 2005, 141 well owners have
taken corrective actions due to high levels of arsenic.
100% of new wells are tested for arsenic through well
regulation. If arsenic is found exceeding the drinking water
standard new wells are drilled or a treatment system is
implemented.
Type I systems must test for arsenic and include the detectable
results in a Consumer Confidence Report (CCR). Type II
systems that serve at least 25 persons must sample once every
six years or annually if in an area of known contamination.
Three Type I systems (Harbor Cove Apartments, Northfield
Place Nursing home, and St. Louis Center) are under an
Administrative Consent Order (ACO) to address arsenic
concentrations exceeding the drinking water standard.
Corrective actions including installation of either treatment or
replacement wells are in progress for all three systems, with
compliance required by July 2008.
Next Steps:
Encourage individual well owners that have not previously
tested for arsenic to have their water tested. Treatment options
exist that can lower the level of arsenic in individual wells for a
relatively small cost. Consider developing an educational
program on the risks associated with arsenic, testing, and the
relative ease of installing arsenic treatment options. Notify
neighbors when unusually high concentrations are found.